1. Proton-driven plasma wakefield Acceleration (PDPWA)
8/3/2019
Proton-driven plasma wakefield Acceleration (PDPWA)
Motivation
PWFA and PDPWA
Demonstration experiment at CERN
Simulation of SPS beam-driven PWFA
Current status and outlook
Guoxing Xia
Max Planck Institute for Physics
KET Strategie-Workshop, Oct.25-26, 2010, Dortmund
KET Strategie Workshop 2010

2. List of people discussing project
Max Planck Institute for Physics, Germany
A. Caldwell, O. Reimann, H.V.D. Schmitt,
F. Simon, G. Xia
Budker Institute for Nuclear Physics, Russia
K. Lotov
Duesseldorf University, Duesseldorf, Germany
A. Pukhov, N. Kumar
University of California, Los Angeles, CA, USA
W. An, C. Joshi, W. Lu, W.B. Mori
Los Alamos National Laboratory, NM, USA
C. Huang
University of Southern California, CA, USA
P. Muggli
SLAC National Accelerator Laboratory
M. Hogan
CERN, Geneva, Switzerland
R. Assmann, F. Zimmermann, I. Efthymiopoulos,
J.P. Koutchouk
Max Planck Institute for Plasma Physics, Germany
O. Gruelke, T. Klinger
DESY
E. Elsen, B. Schmidt, H. Schlarb, J. Osterhoff
University of College London, London, UK
A. Lyapin, M. Wing
Rutherford Appleton Laboratory, Chilton, UK
R. Bingham
GoLP/Instituto de Plasmas e Fusao Nuclear, IST,
Lisboa, Portugal
J. Vieira, R. A. Fonseca, L.O. Silva
Heidelberg University, Heidelberg, Germany
A. Schoening
Karlsruher Institute for Technology, Germany
A. Mueller, S. Hillenbrand
Ludwig-Maximilians Universität LMU, Germany
T. Tajima

3. Motivation
With an increase of beam energy, the size and cost of modern high energy particle accelerators reach the limit (break down+power)
Plasma can sustain very large electric fields, a few orders of magnitude higher than the fields in metallic structures
The plasma accelerators (laser driven-LWFA or beam driven-PWFA) developed rapidly in last 20 years, GV/m accelerating gradients have been demonstrated in labs
The novel plasma accelerators can potentially minimize the size and cost of future machines
Very high energy proton beams are available nowadays, why not use these proton beam to excite wakefield for electron acceleration?
It will be the PWFA experiment in Europe and first PDPWA experiment around the world.

4. PWFA
8/3/2019
Electron beam (beam energy 42GeV, bunch length 50 fs, bunch charge 2.9 nC)
Plasma (length 85 cm, density 2.7e17 cm-3)
Max. energy gain
43 GeV (85 cm column) = 52 GeV/m !
29 GeV (113 cm column)
Energy spectrum of the electrons in the
GeV range as observed in plane 2
Blumenfeld et al., Nature 445 (2007) 741
KET Strategie Workshop 2010

5. PWFA and PDPWA blow-out flow-in Pros. of PWFA
8/3/2019
PWFA and PDPWA
Pros. of PWFA
Plasma electrons are expelled by space charge of beam, a nice bubble will be formed for beam acceleration and focusing.
The short electron beam is relatively easy to have (bunch compression).
Wakefield phase slippage is not a problem.
Cons. of PWFA
One stage energy gain is limited by transformer ratio, therefore maximum electron energy is about 100 GeV using SLC beam.
Easy to be subject to the hosing instability due to small mass of electrons
Pros. of PDPWA
Very high energy proton beam are available today, the energy stored at SPS, LHC, Tevatron, HERA
SPS (450 GeV, 1.3e11 p/bunch) ~ 10 kJ
LHC (1 TeV, 1.15e11 p/bunch) ~ 20 kJ
LHC (7 TeV, 1.15e11 p/bunch) ~ 140 kJ
SLAC (50 GeV, 2e10 e-/bunch) ~ 0.1 kJ
Cons. of PDPWA
Flow-in regime responds a relatively low field vs. blow-out regime.
Long proton bunches (tens centimeters), bunch compression is difficult.
Wave phase slippage for heavy mass proton beam (small γ factor), especially for a very long plasma channel
blow-out
flow-in
linear response
beam
nonlinear response
KET Strategie Workshop 2010

6. PDPWA p+ e- Drive beam: p+ Witness beam: e- Plasma: Li+
8/3/2019
PDPWA p+ e-
Drive beam: p+
E=1 TeV, Np=1011
σz=100 μm,σr=0.43 mm
σθ=0.03 mrad, ΔE/E=10%
600 GeV e- beam
Witness beam: e-
E0=10 GeV, Ne=1.5x1010
≤1% ΔE/E
in ~500 plasma
Plasma: Li+
np=6x1014cm-3
External magnetic field:
Field gradient: 1000 T/m
Magnet length: 0.7 m
A. Caldwell, K. Lotov, A. Pukhov, F. Simon, Nature Physics 5, 363 (2009).
KET Strategie Workshop 2010

7. A magnetic chicane for bunch compression
8/3/2019
Short proton driver
A magnetic chicane for bunch compression
4 km bunch compressor is required for 1 TeV p+ beam!
G. Xia, A. Caldwell et al., Proceedings of PAC09
KET Strategie Workshop 2010

8. 8/3/2019
Short bunch driver
Self-modulation via plasma wakefield (the transverse two-stream instability modulates the long bunch into many ultra short beamlets at plasma wakelength*.
SPS beam at 5m
1e14 cm-3
*also see A. Pukhov‘s talk
KET Strategie Workshop 2010

9. Demonstration experiment at CERN
8/3/2019
Demonstration experiment at CERN
PS (East Hall Area) and SPS (West Area) could be used for our demonstration experiment
KET Strategie Workshop 2010

10. PS vs. SPS PS, SPS energy: low, high bunch length: long, short
8/3/2019
PS, SPS
energy: low, high
bunch length: long, short
beam intensity: low, high
emittance: big, small
plasma focusing: weak, strong
tunnel length: m, 600m PS
SPS
Energy [GeV] 24
450
Protons/bunch [1011]
1.3
1.15
rms bunch length [cm] 20 12
Rms Transverse emittance [μm]
3.5
rms energy spread [10-4] 5 3
Bunch spacing [ns] 25
Simulation shows that SPS beam can drive a higher plasma wakefield compared to the PS beam. This is largely due to the smaller emittance of the SPS beam. The lower emittance of SPS beam allows the instability to develop before the beam diverges due to the angular spread. PS
smooth and cut beams
SPS-LHC beam
high plasma density
SPS-LHC
smooth and cut beams
K. Lotov
KET Strategie Workshop 2010

11. Demonstration experiment at CERN
8/3/2019
Demonstration experiment at CERN
PDPWA has the potential to accelerate electron beam to the TeV scale in a single stage. As a first step, we would like to demonstrate the scaling laws of PDPWA in an experiment with an existing beam.
kick-off meeting-PPA09 held at CERN last December
A spare SPS tunnel is available for demonstration experiment
Will be the first beam-driven PWFA experiment in Europe and the first PDPWA in the world.
Beam Lines
KET Strategie Workshop 2010

12. Codes benchmarking
8/3/2019
Various particle-in-cell (PIC) codes are used to benchmark the results based on same parameter set. Presently they show very good agreement
KET Strategie Workshop 2010

13. Seeding the instability
Seed the instability via laser or electron beam prior to the proton beam (the instability will not start from random noise, rather from a well-defined seeded field-proposed by C.Joshi)
The instability is seeded via half-cut beam (beam density abruptly increases) nb
Eacc
Efocus np
For SPS half-cut beam, at plasma density np=1014 cm-3 (λp3.33 mm)
A strong beam density modulation is observed,
A nice wakefield structure is excited and
the wakefield amplitude is around 100 MV/m at 5 m plasma.
VLPL results from A. Pukhov

14. Simulations of SPS beam-driven PWFA
8/3/2019
Simulations of SPS beam-driven PWFA
QuickPIC results from C. Huang
Half-cut
SPS beam
@4.8m plasma
(np=1014 cm-3)
Full SPS beam
@ 10m plasma
(np=1014 cm-3)
Beam density modulation
Maximum longitudinal e field is ~120 MV/m
KET Strategie Workshop 2010

15. Simulations of SPS beam-driven PWFA
8/3/2019
Simulations of SPS beam-driven PWFA
nominal SPS beam (Set 3)
Simulation from 2D OSIRIS
Bunch population, Np
1.15x1011
Bunch length, σz
12 cm
Beam radius,σx,y
200 μm
Beam energy, E
450 GeV
Energy spread, dE/E
0.03%
Normalized emittance, εx,y
3 μm
Angular spread, σθ
0.02 mrad
Bunch population, Np
3x1011
Bunch length, σz
8.5 cm
Beam radius,σx,y
200 μm
Beam energy, E
450 GeV
Energy spread, dE/E
0.04%
Normalized emittance, εx,y
2 μm
Angular spread, σθ
0.02 mrad
KET Strategie Workshop 2010

16. Plasma density variation
8/3/2019
LHC beam
w. plasma density ramp
~ 900 MV/m field propagates stably for 200 m!
Increasing the plasma density properly at the moment of developed instability, the wave shift with respect to the main body of the beam will be stopped and one can obtain a stable bunch train that propagates in plasma for a long distance
KET Strategie Workshop 2010

17. Demonstration experiment at CERN
Scientific Goal of Experiments:
Initial goal is to observe the energy gain of 1 GeV in 5 m plasma.
A plan for reaching 100 GeV within 100 m plasma will be developed based on the initial round of experiments
Experimental Setup:
Expected Results:
A long SPS drive beam (without compression) will be used in the first experiment. a self-modulation of the beam due to two-stream instability which produces many ultrashort beam slices at plasam.
The modulation resonantly drives wakefield in the MV/m with CERN SPS beam.
Simulation shows with the optimum beam and plasma parameters, ≥ 1 GV/m field can be achieved in the experiment.

18. Current status and outlook
We have very strong simulation teams around the world (UCLA, LANL, BINP, Düsseldorf Univ. IST)
Phone conferences (every two weeks) to exchange the results
A face-to-face meeting next year in London to discuss what to put in the Letter of Intent
The PDPWA demonstration experiment will be proposed as a future project
Simulation shows that working in self-modulation regime, SPS beam can excite the field around 1 GV/m with a high density plasma.
Future experiment will be carried out based upon the first round experiments.
Thanks for your attention !

19. Backup

20. PWFA
PWFA (driving force: space charge of drive beam displaces the plasma electrons; restoring force: plasma ions exert the restoring force to the plasma electrons=> space charge oscillations)
The longitudinal fields can accelerate and decelerate the beam, and plasma structure has the strong focusing forces to the beam.
For longitudinal symmetric bunch, the transformer ratio is limited to 2
Working in blow-out regime (beam density > plasma density), the wakefield is very suitable for low emittance beam acceleration (SLAC E-167, FACET)
*R.D. Ruth et al, SLAC-PUB-3374

21. PDPWA-based LC Concept for high repetition rate of proton driven
8/3/2019
Concept for high repetition rate of proton driven
plasma wakefield acceleration
3 ring + injectors + recovery
Other schemes: e- e- collider; e- p collider
V. Yakimenko, BNL, T. Katsouleas, Duke, 2009
KET Strategie Workshop 2010 21

22. PDPWA-based LC
8/3/2019
A. Seryi, Advanced Accelerator Concepts-AAC 2010, USA
KET Strategie Workshop 2010

23. Possible timeline 2010 2011 2012 2013 2014 2015 Letter of Intent
Technical Design
Beamline assembly
Plasma cell R&D
Construct plasma cell
Optical sampling R&D
Optical sampling setup
Spectrometer R&D
Spectrometer setup
Measure beam modulation
Seeded modulations
Design electron injection
Accelerate electrons